So2 groups

Sulfones. Sulfones, R — SO2—R, are named in an analogous manner to sulfoxides, using the word sulfone in place of sulfoxide. In prefixes, the less senior radical is followed by -sulfonyl-. When the > SO2 group is incorporated in a ring, the compound is named as a dioxide. 

In most cases, the behaviour of sulphones at the cathodic interface (obviously rendered basic when insufficiently buffered due to the accumulation of electrogenerated bases) may be strongly modified by the presence of vicinal CH groups in the a position to the SO2 group. These acidic groups may transfer protons and are often responsible for low yields of the cleavage processes or for undesirable isomerization reactions. 

The —SO2 group is linked to an aliphatic carbon. Low current yields could be due to hydrogen evolution. TEAOT, Et N tosylate TEAI, Et NI. 

Data are also available with a-acetylenic aliphatic sulphones, which involve only two steps i.e., saturation of the triple bond without subsequent cleavage of the Quphaiic—S bond, since it is not reactive. However, the introduction of an aromatic ring to the SO2 group does not lead, contrary to what is observed with enones, to a potential shift toward less reducing potential values. Thus, the aromatic moiety introduced apparently does not bring any additional conjugation effect but even seems to decrease the activation of the unsaturated bond, as shown by data in Tables 6 and 7 where most of the potentials refer to the same saturated calomel electrode under similar experimental conditions. 

The symbols have their usual meanings (] ). From measured values of NTj and ri on a poly (butene-1 sulfone) of degree of polymerization 700 the values of t (in nanosec.) shown in Table III are obtained. The discrepancy between the values of from NT and from ri, particularly marked for the side-chain motions, indicates the inadequacy of the single-Tg model. Nevertheless it is evident that the backbone motions are relatively rapid. (Comparison to polybutene-1 (jW) shows that SO2 groups retard the motion of the copolymer chains by a factor of about 50.) The question now becomes why are these rapid motions NMR-active but dielectrically inactive One possible type of motion which would account for this is shown in Fig. 9. Five backbone bonds and six main-chain atoms are involved, i.e. the sequence C-S-C-C-S-C, with concerted segmental transitions about two C-S bond, allowing interconversion... 

The incorporation of SO2 groups into the main chain of poly(phenylene ether)s leads to poly(phenylene ether sulfone)s. The preferential synthetic routes are ... 

Sulfur atoms extraneous to the heteropentalene system in (4 X = S) can be oxidized by MCPBA to SO and SO2 groups in 64-70% yields <85JCS(P2)833>. Arsenic pentafluoride coordinates to the thiadiazole ring of (59 R = Cl) as shown in (15) (x-ray analysis) <86ZN(B)162>, whereas (rj -ethene)bis(triphenyl-phosphane)platinum(0) inserts into the thiadiazole ring to give a new six-membered metallocycle <86CB366>. 

The symmetric and asymmetric stretching modes of the SO2 group in different fused-ring systems containing thietane oxide have been established and discussed. ... 

Azasulfonamidopeptides, in which an a-amino acid residue is replaced by the -NH-NR-SO2- group, also appear to be of interest as models for the transition state of peptide-bond hydrolysis. As they are potential proteinase inhibitors, the routes for their synthesis have been described. 114 ... 

The rearrangement of the /V-phosphinoyl-O-sulfonylhydroxylarninc (268) (with 57% enrichment with one 180 atom in the SO2 group) to the sulfonamide (269) (43.7% enriched with one 180 atom) occurs with Bu NH2 in dichloromethane via the phosphonamidic-sulfonic anhydride intermediate (270).245 The rearrangement of the O-phosphinoyl compound (271) with /-butoxide gives the phosphonamidic-phosphinic... 

In a few cases pyrolysis and ring contraction occurs under simultaneous loss of carbon-fragments (mostly ethano units because of synthetic reasons). The benzylic side of the disulfone undergoes recombination, whereas the ethano bridge and both the SO2 groups become cleaved and eliminated. 

From presently known structural data, the orientation of the SO2 group in most SP complexes can be rationalized by considering the effect of basal donors and acceptors on the ML4(S02) molecular orbitals. The factors involved in determining the rotational orientation of the bent axial nitrosyl in MNO square-pyramidal complexes have been considered extensively by several authors For convenience, we reproduce two rules, which may be of some utility in rationalizing orientational features of the SO2 complexes discussed here (see especially Ref. 48 for underlying assumptions) (1) (a) In... 

The reaction is carried out in methanol at 20 °C. It is apparent from equations (59) and (60) that the central sulfur atom originates from the sulfide. Cyclic thiosulfonates result in chainlike trisulfanes with chain-terminating SO2 groups (equation 61). ... 

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